Normal binocular visual perception requires a degree high degree of similarity in the presentation of images formed by the right and left eyes and presented to the visual centers of the brain to generate a single visual perception. In order to compare the similarity of optical quality and other ocular characteristics of the right and left eyes with the technique of the present invention, It is a necessity to predetermine certain ocular and optical characteristics of a monocular state of each of the eyes. Such determinations include (1) the individual alignment of the right and left eye to a fixation target, (2) the individual ocular refractive status of the right and left eye and (3) other elements contained in the wavefront that are found to correlate with or predispose to, ocular-optical impediments to successful visual integration of the right and left visual image to produce normal single vision. Such impediments result in or are associated with Amblyopia, Strabismus, Binocular Balance and some reading difficulties.
Amblyopia is a neurological disease resulting in Central Nervous System (brain) neuro-pathologic changes that are related either as a cause or result of some underlying abnormality in the monocular and binocular state. Most modern thought is that individual difference between the two eyes, either in alignment or refractive power or a combination of the two, results in an inability of the two eyes to generate individual right and left images that can be converted into a single mental perception by the brain's visual centers. In the case of misalignment, the eyes are pointing in different directions and the images generated by the eyes cannot be blended together into a single perception. In the case of anisometropia (optical refractive powers of the eyes being different), the images are of different optical size, with one eye more out of focus as compared to the other eye. As a result, the differently-sized images cannot be fused into a single visual image. Frequently, both of these situations are found in Amblyopia. Determining abnormalities in the right and left eye and binocular relationships that result in dissimilarity of image formation frequently predict presence of the amblyopic condition. Another aspect that is less appreciated is that an abnormal neural state affects changes in the eyes by some type of reverse bio-feedback mechanism going from the brain to the eyes. This abnormal neural-feedback to the eyes could result in an abnormality of development or innervation of the extra-ocular muscles. Neurologic innervation, neural disease processes such as optic neuritis occurring during times of visual development, can account for developmental abnormalities of ocular development and or optical configuration of the eyes, all or part of which may result in some of those extreme ocular abnormalities associated with an amblyopic condition.
Evaluation of binocularity of a subject by a trained clinician is generally a subjective process. In the simplest format, such an evaluation is made simply by observing whether both pupils of a subject are centered in the eye fissure, i.e. there is an equal amount of white on both sides of the iris of both eyes while the subject is gazing at a fixed point. In addition, there are several other methods of determining more precisely the presence of binocular cooperation, or integration of the images into a single mental visual perception. Some of these methods include the “Cover/Cover/Uncover” Test of fixation and alignment, or the Stereoscopic Vision and certain Electro-physiologic measurements of visual response found in brain waves in response to a visual stimulus. However, such evaluations are generally dependent on cooperation of the subject and skill of the clinician. For instance, getting a pre-verbal child to gaze at a fixed point to determine individual fixation may be a problem in itself.
A number of devices have been constructed to optically evaluate Wavefront aberrations. In these devices, monocular refractive characteristics of optical power are used to identify and extract location, degree and kind of optical degradation existing within the pupillary aperture. Such knowledge permits precise remedial corneal contouring in order to correct the refractive error. However, these devices do nothing with respect to identification of problems related to visual integration of separate images from the right and left eye into a single mental perception.
Applicants method additionally permits a mathematical description that when plotted, results in a visual “profile” of a disease process found in broad groups of persons suffering with similar ocular states or diseases. This is accomplished by mathematically summing the individual algorithmic parameters of a particular person with those corresponding parameters of other like persons with similar diseases. Once accomplished and entered into a spread sheet, any or all of a number of statistical techniques may be utilized to generate statements concerning these group parameters of disease or inherent optical-ocular condition. In this manner, any ocular Wavefront image of an individual may be expressed statistically as possessing some degree of probability of being contained in some known and statistically defined disease grouping. All eye conditions and diseases, such as Amblyopia, Strabismus, Refraction, Cataracts and Retinal diseases, along with certain medical conditions that present an ophthalmic manifestation such as diabetes, hypertension, brain tumor and others may be approached in like fashion.
It is one object of this invention to extract a plurality of statistical relationships from a digital image of eyes of a subject, and to determine binocular status of the eyes from these relationships. It is another object of this invention to present such statistical relationships in a manner to allow a clinician to identify eye problems associated with binocularity. Other objects will become clear upon a reading of the following specification.